Some wireless mobile equipment (called mobile station, MS, user equipment or UE in 3GPP terminology such as GSM, but also called access terminal, etc. in various literature) use a SIM/USIM card (subscriber identity module/universal subscriber identity module). This card can a subscriber's identity for security and authentication purposes. Some UEs have multi-SIM capability so a user can engage in calls on two different subscriptions. These two subscriptions might be on the same network or on different networks. Some multi-SIM mobile devices only utilize a single transceiver, which is shared for use by both subscriptions while some multi-SIM mobile devices utilize separate transceiver for each SIM.
In today's highly developed wireless industry, the wireless spectrum is essentially fully utilized to meet the ever increasing capacity demand. However, the more loaded a network is, the more interference it has. This presents a challenge to a mobile UE, as it is difficult to maintain an ongoing call with an acceptable quality of service (QoS) in such interference-limited conditions. In live networks, such interference limited conditions frequently occur. In these conditions, a network may not be able to fully utilize its capacity, and user experience can suffer. UEs operating according to GSM standards follow a specified burst structure to identify a training sequence code (TSC) at the middle of each burst, and then work out the fine details for time and frequency tracking. These parameters provide the prerequisites for an interference cancellation algorithm to work well. However, in a network with heavy interference, a UE may have difficulty performing time and frequency tracking.